/*
 * Copyright (C) 2012 Roman Yakovenko <b179a9@gmail.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
 * of the Software, and to permit persons to whom the Software is furnished to do
 * so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

package com.b17.net.protocol;

import com.b17.crypto.core.Utils;
import com.b17.net.exception.FragmentationTimeoutException;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

/**
 * Created by b17
 * 3/4/12 10:47 AM
 */

public class FragmentationReader {

    public static final int TIMEOUT = 5 * 60 * 1000;

    public static final int DELAY = 30;

    public static final int ACK_SUCCESS = 1;
    public static final int ACK_FAILED = 0;

    InputStream inputStream;
    OutputStream outputStream;

    public FragmentationReader(InputStream inputStream, OutputStream outputStream) {
        this.inputStream = inputStream;
        this.outputStream = outputStream;
    }

    public byte[] read() throws IOException, InterruptedException, FragmentationTimeoutException {
        byte[] fragmentsHeader = new byte[4];
        inputStream.read(fragmentsHeader);
        outputStream.write(ACK_SUCCESS);

        int fragmentsCount = Utils.toInteger(fragmentsHeader);
        byte[][] fragments = new byte[fragmentsCount][];

        for (int i = 0; i < fragmentsCount; i++) {
            int fragmentSize;
            int fragmentTime = 0;
            while ((fragmentSize = inputStream.available()) == 0) {
                if (fragmentTime >= TIMEOUT) {
                    outputStream.write(ACK_FAILED);
                    throw new FragmentationTimeoutException();
                }
                Thread.sleep(DELAY);
                fragmentTime += DELAY;
            }
            byte[] fragment = new byte[fragmentSize];
            inputStream.read(fragment);
            fragments[i] = fragment;
            outputStream.write(ACK_SUCCESS);
        }
        return join(fragments);
    }

    private byte[] join(byte[][] bytes) {
        int totalSize = 0;
        for (int i = 0; i < bytes.length; i++) {
            totalSize += bytes[i].length;
        }
        byte[] result = new byte[totalSize];
        for (int i = 0, offset = 0; i < bytes.length; i++) {
            System.arraycopy(bytes[i], 0, result, offset, bytes[i].length);
            offset += bytes[i].length;
        }
        return result;
    }
}
